To date, the highest light extraction for an LED (light emitting diode) chip and LED package (more chip-specific than package-specific) has generally been with small LED chips (˜300 micrometers×300 micrometers) as compared with “power chips” (LEDs of ˜0.9-1 mm×0.9-1 mm).
Efforts have been ongoing to develop ways by which solid state light emitting devices can be used in place of incandescent lights, fluorescent lights and other light-generating devices in a wide variety of applications. In addition, where light emitting diodes (or other solid state light emitting devices) are already being used, efforts are ongoing to provide light emitting diodes (or other solid state light emitting devices) which have improved energy efficiency.
Various efforts have been directed at improving the performance of light emitting diodes on a common substrate. For example:
U.S. Pat. No. 6,635,503 describes cluster packaging of light emitting diodes;
United States Patent Application Publication No. 2003/0089918 describes broad spectrum light emitting devices and methods and systems for fabricating broad spectrum light emitting devices;
U.S. Pat. No. 6,547,249 describes monolithic series/parallel light emitting diode arrays formed on highly resistive substrates;
U.S. Pat. No. 7,009,199 describes electronic devices having a header and anti-parallel connected light emitting diodes for producing light from AC current;
U.S. Pat. No. 6,885,035 describes multi-chip semiconductor light emitting diode assemblies;
U.S. Pat. Nos. 7,213,942 and 7,221,044 each describe single chip integrated LEDs adapted for direct use with a high AC or DC voltage;
United States Patent Application Publication No. 2005/0253151 describes a light emitting device operating on a high drive voltage and a small drive current;
Japanese Patent Publication No. 2001-156331 describes a plurality of nitride semiconductor layers formed on the same substrate, where the layers are electrically separated from each other and each nitride semiconductor layer is electrically connected with a conductive wire;
Japanese Patent Publication No. 2001-307506 describes two or more light emitting diodes being formed on the same semiconductor substrate; and
United States Patent Application Publication No. 2007/0202623 describes a wafer level package for very small footprint and low profile white LED devices.